Gymnosperms

Question 1

Seed - what? what components (3)?

Answer 1

seed - fertilized, mature ovule containing:
- an embryo
- stored food reserves
- protective (seed) coat

Question 2

do gymnosperms have secondary growth?

Answer 2

Yes!

Question 3

Gymnosperm characteristics:

Answer 3

• first of seed plants
• exposed nature of seeds
• seeds produced on surface of sporophylls or STROBULI instead of enclosed within a fruit in angiosperms (no flower/fruit)
• seed-bearing and pollen-bearing sporophylls often arranged in cones
• vasculature, true roots/stems/leaves
• secondary growth, not dependent on water for fertilizaion

Question 4

Gymnosperms: seed-bearing and pollen-bearing _____ often arranged in _____

Answer 4

sporophylls
cones

Question 5

Gymnosperms: hetersporous or homosporous?

Answer 5

heterosporous

Question 6

gymnosperms: gametophyte & sporophyte relationship

Answer 6

gametophyte contained and dependent on sporophyte

Question 7

gymnosperms phyla (4):

Answer 7

cycadophyta
gnetophyta
ginkgophyta
coniferophyta

Question 8

ginkgophyta: monoecious or dioecious?

Answer 8

dioecious- separate pollen and seed-producing plants

Question 9

Coniferophyta characteristics

Answer 9

• largest living gymnosperm group
• woody cones and wind aids pollination/seed dispersal BUT not all have woody cones!
• specialized leaves “needles” & cones allow plants to live in cold/dry climates
  (low surface area, thick epidermis, sunken stomata -> lower water loss)

Question 10

pine - ovule/pollen characteristics

Answer 10

monoecious - ovulate (female cone) & pollen cones (male strobili) develop on same plant (male is higher)
- promote cross-pollination and can pollinate self
- ovule has single megasporocyte in megasporangium (nucellus)

Question 11

pine - megasporocyte anatomy

Answer 11

-> integument (2n): surrounds megasporangium
-> micropyle: opening in integument, allow fertilization
-> have woody scales w pair of ovules at base

Question 12

pine - pollen grain anatomy

Answer 12

meiosis produces microspores developing into pollen grains
pollen grains - 4 cells and a pair of air sacs

Question 13

pine life cycle 1st year

Answer 13

• microspores form pollen grains (meiosis), lands on drops of fluid on the ovule MICROPYLE
• pollen grains GERMINATE: pollen tube emerges from pollen grain, enters through micropyle, digests nucellus; 2 sperm cells produced in pollen tube
• megaspore development begins ONLY after pollen grain germinates(pollination): megasporocyte undergoes meiosis, producing 4 megaspores (1 survives, 3 degenerate)
  (during this month-long process, ovule is sealed off from more pollination)
• over months, surviving megaspore develops into female gametophyte w argonia at micropyle end. nucellus is food source for gametophyte

Question 14

pine life cycle 2nd year

Answer 14

• female gametophyte and archegonia (2-8, each w one egg) mature
• pollen tube arrives at archegonium (avg 15 months from pollination)
• fertilization: one sperm per pollen tube fuses w egg, forming zygote (other sperm degenerates); if pollinated with >1 pollen grain, can fertilize more than one egg (archegonium) at a time

Question 15

pine life cycle after fertilization:
food source =?
integument=?
scales =?

Answer 15

food source -> gametophyte (1n) instead of nucellus
seed coat -> from integument (2n)
embryo (2n)
wing forms from ovuliferous scales & help wind dispersal